According to another poster about 2 weeks at ~ $285k per day, so about $3,990,000 extra. Depending on the cargo and late penalties $4.5 mil is in the range of acceptable charges.
The $285k was not an estimation of what it costs to run a ship per day. They merely divided $4M by 14. So it was an estimation of how much saving two weeks to go around is worth to the highest bidder, per day.